We went thru the same thing when we adopted Taffy, I called the Humane Society back when we found out she was in heat, and had tied with my Harry boy and they basically apologized for their error and told me it was MY fault for having an intact male at home..
. I hope your humane society is better than the one we adopted Taffy from.. she will be spayed in a couple of weeks free of charge by the clinic my son works for, they could not beleive what happen.
Best of luck with your baby..
hugs,
Carmen in nj